An electrode material for alkaline pure water electrolysis oxygen evolution reaction, its synthesis method and application

Abstract

The present invention discloses an electrode material for alkaline pure water electrolytic oxygen evolution reaction, its synthesis method and application. First, the nickel substrate is pretreated, and the pretreated nickel substrate is placed in a vacuum drying oven; the metal salt containing Sn 4+ is dissolved in deionized water and stirred until completely dissolved to obtain a precursor solution; the nickel substrate is completely immersed in the prepared precursor solution and left standing. After standing, the nickel electrode is taken out and dried to obtain the electrode material for alkaline pure water electrolytic oxygen evolution reaction. This electrode material has a uniform and dense two-dimensional nanosheet array structure. The electrode material synthesized by the method of the present invention has a good catalytic effect on the electrolytic oxygen evolution reaction of alkaline simulated seawater. In 1M KOH medium, the overpotential only needs 300-330 mV at a current density of 10 mA cm ‑2 . In 1M KOH medium, the stability at a current density of 500 mA cm ‑2 can be up to 24 h without inactivation.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparing two-dimensional nanomaterials containing tin and nickel, and particularly relates to an electrode material for the oxygen evolution reaction in alkaline pure water electrolysis, a synthesis method thereof, and an application thereof. Background Art

[0002] Among various hydrogen production technologies, driving electrochemical water splitting to produce hydrogen using intermittent renewable energy sources (such as solar energy, wind energy, and tidal energy) shows significant application potential due to its clean, green, and pollution-free characteristics.

[0003] The electrochemical water splitting process includes two key half-reactions: the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode. Compared with the two-electron transfer process of HER, OER involves a complex four-electron transfer path and is accompanied by a series of reaction steps such as the adsorption and dissociation of OH - , the formation of O-O intermediates, and the desorption of O2, resulting in significantly slow kinetics and becoming the bottleneck of the entire electrochemical water splitting process. Therefore, how to design and develop efficient OER catalysts to improve the reaction kinetic efficiency is the key to promoting the development of electrolytic water hydrogen production technology. It should be noted that in alkaline media, due to the much higher concentration of OH⁻ than in acidic or neutral media, the OER reaction kinetics are significantly improved, and alkaline conditions are considered more conducive to the realization of electrochemical water splitting. Although noble metal catalysts based on IrO2 and RuO2 exhibit excellent catalytic performance in OER, their high cost, low abundance, and poor long-term stability greatly limit their industrial applications. Therefore, developing highly active, low-cost, and stable OER catalysts based on earth-abundant elements has become the core goal of the research and application of alkaline water electrolysis technology. In recent years, non-noble metal-based materials have gradually become a research hotspot due to their lower cost, excellent catalytic performance, and good stability. Among them, nickel-based layered double hydroxides (Ni-LDH) show broad industrial application prospects due to their easy synthesis, remarkable structural stability, and excellent OER activity. By regulating the structure of Ni-LDH and optimizing the surface chemical environment, its catalytic activity can be further improved and its service life can be extended. Therefore, developing highly active, low-cost, and stable OER catalysts based on earth-abundant elements is the key to promoting the development of alkaline water electrolysis technology. Summary of the Invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide an electrode material for the oxygen evolution reaction in alkaline pure water electrolysis, a synthesis method thereof, and an application thereof. This electrode material has better electrocatalytic performance and excellent stability than the original substrate in an alkaline pure water electrolyte, and its catalytic activity does not significantly decrease after long-term operation. It is a promising electrode material for alkaline pure water electrolysis.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] The present invention provides an electrode material for the oxygen evolution reaction in alkaline pure water electrolysis. The electrode material includes a nickel substrate and a surface dense catalytic layer in-situ formed on the nickel substrate by a solution impregnation method. The surface dense catalytic layer is an oxide or hydroxide containing nickel and tin.

[0007] Furthermore, the electrode material has a uniform and dense two-dimensional nanosheet array structure, with the lateral thickness of the nanosheets being 20 - 60 nm and the longitudinal length being 200 - 500 nm.

[0008] The present invention provides a synthesis method for the electrode material for the oxygen evolution reaction in alkaline pure water electrolysis, which includes the following steps:

[0009] 1) First, pretreat the nickel substrate, and store the pretreated nickel substrate in a vacuum drying oven;

[0010] 2) Dissolve the metal salt containing Sn 4+ in deionized water, and stir until completely dissolved to obtain a precursor solution;

[0011] 3) Completely immerse the nickel substrate obtained in step 1) in the precursor solution prepared in step 2) and let it stand for a period of time. After standing, take out the nickel electrode and dry it to obtain the electrode material for the oxygen evolution reaction in alkaline pure water electrolysis.

[0012] Furthermore, the pretreatment process of the nickel substrate in step 1) is as follows:

[0013] Use acetone, acid solution, deionized water, and absolute ethanol as cleaning agents for the nickel substrate respectively, and ultrasonically clean it for 5 - 15 min in an ultrasonic environment to remove organic substances, oxides, and acids on the substrate surface; the acid solution includes HCl, H2SO4, or HNO3.

[0014] Furthermore, in step 1), the nickel substrate is nickel foam, nickel mesh, or nickel foil.

[0015] Furthermore, in step 2), the metal salt containing Sn 4+ is tin tetrachloride, tin fluoride, tin tetrachloride hydrate, or tin fluoride hydrate; the concentration of the tin salt is 0.05 - 0.5 M, and the stirring time is 10 - 60 min.

[0016] Furthermore, in step 2), the concentration of the tin salt is 0.1 - 0.2 M; the stirring time is 15 - 30 min.

[0017] Furthermore, in step 3), the impregnation time is 15 - 240 min; the impregnation temperature is 20 - 80 °C; the drying temperature is 20 - 100 °C.

[0018] Furthermore, in step 3), the impregnation time is 30 - 120 min; the impregnation temperature is 40 - 60 °C; the drying temperature is 60 - 80 °C.

[0019] The present invention also provides an electrode material prepared by the above synthesis method as an oxygen evolution reaction electrode material for alkaline pure water electrolysis.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1) First, the nickel substrate is pretreated in the present invention, and the treated nickel substrate is stored in a vacuum drying oven; then a metal salt containing Sn 4+ is dissolved in deionized water and stirred until completely dissolved to obtain a precursor solution; then the nickel substrate is completely immersed in the prepared precursor solution and left standing for a period of time. After standing, the nickel electrode is taken out and dried to obtain an electrode material for oxygen evolution reaction of alkaline pure water electrolysis. This electrode material has a uniform and dense two-dimensional nanosheet array structure;

[0022] 2) The electrode material synthesized by the method of the present invention has good catalytic effect on oxygen evolution reaction of alkaline simulated seawater electrolysis. In 1 M KOH medium, the overpotential is only 300 - 330 mV at a current density of 10 mA cm -2 , and the stability at a current density of 500 mA cm -2 in 1 M KOH medium can last up to 24 h without inactivation;

[0023] 3) The synthesis method of the present invention is simple and easy to implement. The synthesized electrode material has better electrocatalytic performance and excellent stability than the original substrate in alkaline pure water electrolyte, and the catalytic activity does not decrease significantly after long-term operation. It is a promising electrode material for alkaline pure water electrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the X-ray diffraction pattern of the Sn@NF electrode material prepared in Examples 1, 2, and 3 of the present invention;

[0025] Figure 2 It is the scanning electron microscope image of the Sn@NF electrode material prepared in Example 1 of the present invention. Figure 2 In FIG. (a) and Figure 2 FIG. (b) in it are the scanning electron microscope images of Sn@NF (0.2 M) at different magnifications in the same area;

[0026] Figure 3 It is the linear sweep voltammogram of Sn@NF (0.2 M) and NF prepared in Example 1 of the present invention;

[0027] Figure 4Linear sweep voltammograms of Sn@NF(0.05M) and NF prepared in Example 2 of the present invention;

[0028] Figure 5 Linear sweep voltammograms of Sn@NF(0.1M) and NF prepared in Example 3 of the present invention;

[0029] Figure 6 Two-electrode stability test of the Sn@NF(0.2M) and NF electrodes prepared in Example 1 of the present invention at a current density of 500 mAcm -2 in 1 M KOH;

[0030] Figure 7 Two-electrode stability test of the Sn@NF(0.05M) and NF electrodes prepared in Example 2 of the present invention at a current density of 500 mAcm -2 in 1 M KOH;

[0031] Figure 8 Two-electrode stability test of the Sn@NF(0.1M) and NF electrodes prepared in Example 3 of the present invention at a current density of 500 mAcm -2 in 1 M KOH. Detailed implementation mode

[0032] The present invention will be further described below in conjunction with embodiments, but the scope protected by the present invention is not limited to the described scope. Example 1

[0033] In this example, the preparation method of the Sn@NF electrode material by treating nickel foam with a tin metal solution is as follows:

[0034] 1) Preparation and preservation method of pretreated nickel foam (NF): Acetone, 2 M HCl, deionized water, and absolute ethanol are used as cleaning agents respectively, and ultrasonically treated for 10 min in an ultrasonic environment to remove organic substances, oxides, and acids on the surface of the NF (3×2 cm 2 ) substrate. The treated NF substrate is placed in a vacuum drying oven for preservation to avoid oxidation by air;

[0035] 2) Weigh 10 mM (3.506 g) of SnCl4·5H2O and dissolve it in 50 ml of deionized water, and stir until completely dissolved;

[0036] 3) Immerse the pretreated NF substrate completely in the precursor solution at a temperature of 60°C for 60 min, then take it out and vacuum dry it overnight at 60°C. The obtained electrode material sample is labeled as Sn@NF(0.2M).

[0037] The above-prepared electrode material was subjected to X-ray diffraction analysis, asFigure 1 As shown in the figure, it can be observed that the characteristic peak positions of its XRD match those of standard elemental nickel XRD, and there are no obvious characteristic peaks of Sn-containing species, indicating that the material has low crystallinity or an amorphous structure.

[0038] The as-prepared electrode material was subjected to morphological analysis, and its scanning electron microscope image is as Figure 2 shown, showing that the material has a uniform and dense two-dimensional nanosheet array structure, the thickness of the nanosheets is 20 - 60 nm, and the nanosheets can expose more active sites.

[0039] The Sn@NF(0.2M) electrode material prepared by treating nickel foam with the above-mentioned tin metal solution was used as the anode oxygen evolution reaction (OER) electrode material for alkaline pure water electrolysis, and its electrochemical performance was evaluated. The test method is as follows:

[0040] The previously prepared Sn@NF(0.2M) electrode material (2×3 cm 2 ) was cut into 1×1 cm 2 ; A platinum sheet electrode clip was used to clamp one side of the electrode material for fixation; A standard three-electrode system was used for testing. The prepared electrode material Sn@NF(0.2M) was used as the working electrode, the counter electrode was a 1×1 cm platinum foil 2 , the reference electrode was Hg / HgO(0.098 V vs.RHE), the electrolyte was 1 M KOH, and the effective working area was maintained at 1 cm 2 . First, the electrode was activated by cyclic voltammetry (CV) in 1 M KOH electrolyte, the voltage setting range was 0.1 V - 1.0 V, and the scan rate was 50 mV·s -1 for 50 cycles; Then, linear sweep voltammetry (LSV) was performed in the electrolyte, the voltage setting range was 0 V - 1.2 V vs.Hg / HgO, and the scan rate was 5 mV·s -1 . Subsequently, electrochemical impedance spectroscopy (EIS) was performed on the material at a voltage of 0.65 V vs.Hg / HgO and a frequency range from 100 kHz to 0.01 Hz to obtain the solution (1 M KOH) resistance; Finally, a two-electrode system was used to perform long-term stability testing on the Sn@NF(0.2M) electrode material in 1 M KOH electrolyte under a constant current of 500 mA cm -2 .

[0041] The test results are as Figure 3 and Figure 6 shown. It can be seen from this figure that: at 10 mA cm -2 , the overpotential only needs 304 mV, and at 500 mA cm -2The stability can reach 24 h. Therefore, this catalyst is an alkaline pure water electrolytic oxygen evolution reaction (OER) electrode material with high activity and long-term stability. Example 2

[0042] In this example, the preparation method of the Sn@NF electrode material by treating nickel foam with a tin metal solution is as follows:

[0043] 1) Preparation and preservation method of pretreated nickel foam (NF): Acetone, 2 M HCl, deionized water, and absolute ethanol were used as cleaning agents respectively, and ultrasonically treated for 10 min under ultrasonic conditions to remove organic substances, oxides, and acids on the surface of the NF (3×2 cm 2 ) substrate. The treated NF substrate was placed in a vacuum drying oven for preservation to avoid oxidation by air;

[0044] 2) Weigh 2.5 mM (0.877 g) of SnCl4·5H2O and dissolve it in 50 ml of deionized water, and stir until completely dissolved;

[0045] 3) Immerse the pretreated NF substrate completely in the precursor solution at 80 °C for 90 min, then take it out and vacuum dry overnight at 60 °C. The obtained catalyst sample is labeled as Sn@NF (0.05M).

[0046] The Sn@NF (0.05M) electrode material prepared by treating nickel foam with the above tin metal solution was used as an electrode material for the oxygen evolution reaction (OER) at the anode of alkaline pure water electrolysis, and the electrochemical performance was evaluated. The test method is as follows: The same as in Example 1.

[0047] The test results are as Figure 4 and Figure 7 shown. It can be seen from this figure that: at 10 mA cm -2 , the overpotential only needs 326 mV, and the stability at 500 mA cm -2 can reach up to 24 h. Example 3

[0048] In this example, the preparation method of the Sn@NF electrode material by treating nickel foam with a tin metal solution is as follows:

[0049] 1) Preparation and preservation method of pretreated nickel foam (NF): Acetone, 2 M HCl, deionized water, and absolute ethanol were used as cleaning agents respectively, and ultrasonically treated for 10 min under ultrasonic conditions to remove organic substances, oxides, and acids on the surface of the NF (3×2 cm 2 ) substrate. The treated NF substrate was placed in a vacuum drying oven for preservation to avoid oxidation by air;

[0050] 2) Weigh 5 mM (1.753 g) of SnCl4·5H2O and dissolve it in 50 ml of deionized water, stirring until completely dissolved;

[0051] 3) Immerse the pretreated NF substrate completely in the precursor solution at 60 °C. After 120 min of immersion, take it out and dry it overnight under vacuum at 60 °C. The obtained catalyst sample is labeled as Sn@NF (0.1M).

[0052] Apply the above-prepared Sn@NF (0.1M) electrode material obtained by treating nickel foam with the tin metal solution to the anode oxygen evolution reaction (OER) electrode material for alkaline pure water electrolysis, and conduct electrochemical performance evaluation. The test method is as follows: the same as in Example 1.

[0053] The test results are as Figure 5 and Figure 8 shown. It can be seen from this figure that: at 10 mA cm -2 the overpotential only needs 300 mV, and the stability at 500 mA cm -2 can last up to 24 h.

[0054] Comparative Example 1:

[0055] 1) Preparation and preservation method of pretreated nickel foam (NF): Use acetone, 2 M HCl, deionized water, and absolute ethanol as cleaning agents respectively, and ultrasonicate for 10 min each in an ultrasonic environment to remove organic substances, oxides, acids, etc. on the surface of the NF (3×2 cm 2 ) substrate. The treated NF substrate is placed in a vacuum drying oven for preservation to avoid oxidation by air;

[0056] 2) Take 50 ml of deionized water and heat it to 60 °C. Immerse the pretreated NF substrate completely in the obtained deionized water at 60 °C. After 60 min of immersion, take it out and dry it overnight under vacuum at 60 °C. The obtained electrode material sample is labeled as NF-1.

[0057] Apply the above-prepared NF-1 electrode material to the anode oxygen evolution reaction (OER) electrode material for alkaline pure water electrolysis, and conduct electrochemical performance evaluation. The test method is as follows: the same as in Example 1.

[0058] The test results are as Figures 3 to 5 and Figures 6 to 8 shown. It can be seen from the figure that: at 10 mA cm -2 the overpotential needs 367 mV, and the stability at 500 mA cm -2 is deactivated after only 0.75 h.

Claims

1. A method for synthesizing an oxygen evolution reaction electrode material for alkaline pure water electrolysis, characterized in that The electrode material includes a nickel substrate and a surface dense catalytic layer in-situ formed on the nickel substrate by a solution impregnation method, and the surface dense catalytic layer is an oxide or hydroxide containing nickel and tin; The electrode material has a uniform and dense two-dimensional nanosheet array structure, and the lateral thickness of the nanosheet is 20 - 60 nm, and the longitudinal length is 200 - 500 nm; It includes the following steps: 1) First, pretreat the nickel substrate, and store the pretreated nickel substrate in a vacuum drying oven; 2) Dissolve the metal salt containing Sn 4+ in deionized water and stir until completely dissolved to obtain a precursor solution; 3) Immerse the nickel substrate obtained in step 1) completely in the precursor solution prepared in step 2) and let it stand for a period of time. After standing, take out the nickel electrode and dry it to obtain the electrode material for the alkaline pure water electrolytic oxygen evolution reaction; The metal salt containing Sn in step 2) 4+ is tin tetrachloride, tin fluoride, tin tetrachloride hydrate or tin fluoride hydrate; the concentration of the tin salt is 0.05 to 0.5 M, and the stirring time is 10 to 60 min.

2. The synthesis method of the alkaline pure water electrolysis oxygen evolution reaction electrode material according to claim 1, characterized in that The process of pretreating the nickel substrate in step 1) is as follows: Use acetone, acid solution, deionized water, and absolute ethanol as cleaning agents for the nickel substrate respectively, and ultrasonically clean for 5 - 15 min respectively in an ultrasonic environment to remove organic substances, oxides, and acids on the substrate surface; the acid solution includes HCl, H2SO4 or HNO3.

3. The synthesis method of the alkaline pure water electrolysis oxygen evolution reaction electrode material according to claim 2, characterized in that In step 1), the nickel substrate is nickel foam, nickel mesh or nickel foil.

4. The synthesis method of the alkaline pure water electrolysis oxygen evolution reaction electrode material according to claim 1, characterized in that In step 2), the concentration of the tin salt is 0.1 - 0.2 M; the stirring time is 15 - 30 min.

5. The synthesis method of the alkaline pure water electrolysis oxygen evolution reaction electrode material according to claim 1, characterized in that In step 3), the impregnation time is 15 - 240 min; the impregnation temperature is 20 - 80 °C; the drying temperature is 20 - 100 °C.

6. The synthesis method of the alkaline pure water electrolysis oxygen evolution reaction electrode material according to claim 5, characterized in that In step 3), the impregnation time is 30 - 120 min; the impregnation temperature is 40 - 60 °C; the drying temperature is 60 - 80 °C.

7. An electrode material prepared by the synthesis method according to any one of claims 1 - 6 is used as an electrode material for the alkaline pure water electrolytic oxygen evolution reaction.

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